ATP UM3 Auto Initialize with Load Flow

[MattMag]

Apologies for posting this on this site rather than the EEUG forum, but there seems to be more activity here !

Has anyone tried in ATPdraw to use the loadflow (FIX SOURCE) feature while at the same time using the Caged rotor induction machine (UM3) auto inititialize feature ?

I'm seeking to set up a model with three type 59 sync machines and some induction motors, and it would appear that the load flow module models the IM as an impedance, leaving the mechanical network "floating". This then leaves the current source that the auto initialize feature adjusts to represent the IM load torque, as "illegal" since it is a current source in a floating sub network.

Most frustrating !

Many Thanks

Matt

 

[Alex68]

Hi MattMag
the biggest frustation is the complete absence of documentation or tutorials for new users like you and me.

I avoid the problem you have found starting the simulation with a motor starting. After 1s the motors are in a steady state, I simulate the transients I need.
It's a bad way but it's the only I found.

Alex68

 

[MattMag]

Hi Alex

Thanks for the post. Its a good way round, and if you use a negative torqe, you can speed up the start up !

I was doing motor starting by using the auto initialisation, with slip set to 100%, and putting in a current source at t=0 to counteract the torque set by the auto init routine. Pretty contrived - but it does ensure that there is no large torque oscillations...

When starting using the manual method, I set speed and all current to zero (this produces the large torqe oscillations) Does anyone know whether these oscillations would occur in reality (after all in practice everything starts from zero?)

Thanks

a less frustrated Matt

 

[Alex68]

Hi Matt
the oscillation are the proof that the simulation is correct!!!
At the instant 0s, you are energising an inductance, so...

I have found the way to consult the old emails of the ATP mailing list...

Alex68